The present invention relates to the quantum state transfer of information between matter and light.
The ability to coherently transfer quantum information between photonic- and material-based quantum systems is a prerequisite for all practical distributed quantum computation and scalable quantum communication protocols. The importance of this process is rooted in the fact that matter-based quantum systems provide excellent long-term quantum memory storage, whereas long-distance communication of quantum information will most certainly be accomplished by coherent propagation of light, often in the form of single photon pulses.
In the microwave domain, coherent quantum control has been obtained with single Rydberg atoms and single photons, and advances have also been made in ion trapping information processing. Particularly, an entangled state of an ion and a photon has been produced. However, to convert a single ion (atom) qubit state into a photonic state, strong coupling to a single cavity mode is required. Trapped atoms or ions localized inside high-finesse cavities offer a natural paradigm for coherent, reversible matter-light interactions, although technical challenges make these systems difficult to realize in practice.
Optically thick atomic ensembles have emerged recently as an alternative for the light-matter interface. Duan, Lukin, Cirac, and Zoller (DLCZ) have made a theoretical proposal aimed at long-distance quantum communication that uses the quantum memory capability of atomic ensembles. Important initial steps toward realization of the DLCZ protocol have been made in which nonclassical radiation has been produced from an atomic ensemble, thereby demonstrating the collective enhancement.
It would be desirable to have systems and methods that provide for the quantum state transfer of information between matter and light.